The Cu(II)‐catalyzed oxidation of ciprofloxacin (CIP) by hexacyanoferrate(III) (HCF) has been investigated spectrophotometrically in an aqueous alkaline medium at 40°C. The stoichiometry for the reaction indicates that the oxidation of 1 mol of CIP requires 2 mol of HCF. The reaction exhibited first‐order kinetics with respect to [HCF] and less than unit order with respect to [CIP] and [OH−]. The products were also identified on the basis of stoichiometric results and confirmed by the characterization results of LC‐MS and FT‐IR analysis. All the possible reactive species of the reactants have been discussed, and a most probable kinetic model has been envisaged. The activation parameters with respect to the slow step of the mechanism were computed, and thermodynamic quantities were also determined.

The kinetics and mechanism of oxidation of nalidixic acid (NA) by permanganate ion in alkaline medium have been studied at 40 ± 1 o C. The Stoichiometry was observed to be 2:1 in terms of mole ratio of permanganate ion and nalidixic acid consumed. The reaction shows first order with respect to oxidant and fractional order in both the substrate and alkali concentration. The oxidation reaction proceeds via an alkali permanganate species that forms a complex with nalidixic acid and the complex then decomposes to give the product. The effects of added products and ionic strength have also been investigated. The main products identified were hydroxylated NA and Mn(VI). A mechanism was proposed on the basis of experimental results. Investigation of the reaction at different temperature allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism.

Soluble colloidal manganese dioxide was formed by reduction of potassium permanganate with sodium thiosulphate in neutral aqueous medium at 25 ºC. The obtained nano-sized colloidal manganese dioxide was found to be dark reddish-brown in color and stable for several months. The formation of manganese dioxide was confirmed by UV-visible spectrophotometer and determination of oxidation state of Mn species in manganese dioxide. The effect of different concentration of sodium thiosulphate on the formation of manganese dioxide was also studied. The nano-sized colloid manganese dioxide was characterized by transmission electron microscopy and Fourier transform infrared spectrophotometer. The formed soluble colloidal manganese dioxide was used as an oxidant in oxidation of ciprofloxacin in perchloric acid medium at 35 ºC. The reaction was first-order concerning to concentration of manganese dioxide and hydrogen ion but fractional order with ciprofloxacin. The results suggest formation of complex between ciprofloxacin and manganese dioxide. The oxidation products were also identified based on stoichiometric and characterization results. Copyright © 2020 BCREC Group. All rights reserved

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The presence and accumulation of antibacterial drugs in environment, may pose threats to the ecosystem and human health. Hence, oxidation process is of significant to minimize possibility of health risk. The present study aimed to uncatalyzed and Cu(II) catalyzed oxidative degradation of antibacterial drug ofloxacin by hexacyanoferrate(III) in aqueous alkaline medium at 40 °C temperature. The stoichiometry of the reaction indicates that the oxidation of 1 mol of ofloxacin requires 2 mol of hexacyanoferrate(III). The uncatalyzed reaction exhibited first order kinetics with respect to [hexacyanoferrate(III)] and [ofloxacin] and less than unit order with respect to [OH − ]. The catalyzed reaction gives first order kinetics with respect to [hexacyanoferrate(III)] and [OH − ] and less than unit order with respect to [ofloxacin]. The products were also identified on the basis of stoichiometric results and confirm by the characterization results of liquid chromatography mass spectroscopy and Fourier transform infrared analysis. The major product of the reaction obtained by the decarboxylation of the quinolones moiety and hence it may retain the antibacterial activity. Uncatalyzed reaction simultaneously occurs with the Cu(II) catalyzed reaction and the following rate law confirms to all experimental data observed in the reaction: k �� = k un + K 1 K 3 k[Cu(II)][OH − ][OFL] K 2 +K 3 [OFL] , where k ′′ = (k un + k c) is the total observed first order rate constant, k un = Pseudo first order rate constant for uncatalyzed reaction, K c = Pseudo first order rate constant for catalyzed reaction. A reaction mechanism accounting for all these experimental results has been suggested.